Change trigger type to AFTER trigger.

During repacking table, if a transaction executes INSERT CONFLICT
ON UPDATE/DO NOTHING, because we define BEFORE trigger on target
table, the contents of operation log table becomes inconsistent
easliy. As a result, pg_reapck fails with a high probability.

To resolve this issue, this changes the trigger type from BEFORE
to AFTER. We define AFTER trigger that is the first of the AFTER
trigger to fire on the table.

regress/sql/repack.sql

@@ -197,16 +197,16 @@ CREATE FUNCTION trgtest() RETURNS trigger AS
 $$BEGIN RETURN NEW; END$$
 LANGUAGE plpgsql;
 CREATE TABLE trg1 (id integer PRIMARY KEY);
-CREATE TRIGGER z_repack_triggeq BEFORE UPDATE ON trg1 FOR EACH ROW EXECUTE PROCEDURE trgtest();
+CREATE TRIGGER a_repack_trigges AFTER UPDATE ON trg1 FOR EACH ROW EXECUTE PROCEDURE trgtest();
 \! pg_repack --dbname=contrib_regression --table=trg1
 CREATE TABLE trg2 (id integer PRIMARY KEY);
-CREATE TRIGGER z_repack_trigger BEFORE UPDATE ON trg2 FOR EACH ROW EXECUTE PROCEDURE trgtest();
+CREATE TRIGGER a_repack_trigger AFTER UPDATE ON trg2 FOR EACH ROW EXECUTE PROCEDURE trgtest();
 \! pg_repack --dbname=contrib_regression --table=trg2
 CREATE TABLE trg3 (id integer PRIMARY KEY);
-CREATE TRIGGER z_repack_trigges BEFORE UPDATE ON trg3 FOR EACH ROW EXECUTE PROCEDURE trgtest();
+CREATE TRIGGER a_repack_triggeq AFTER UPDATE ON trg3 FOR EACH ROW EXECUTE PROCEDURE trgtest();
 \! pg_repack --dbname=contrib_regression --table=trg3
 CREATE TABLE trg4 (id integer PRIMARY KEY);
-CREATE TRIGGER zzzzzz AFTER UPDATE ON trg4 FOR EACH ROW EXECUTE PROCEDURE trgtest();
+CREATE TRIGGER a BEFORE UPDATE ON trg4 FOR EACH ROW EXECUTE PROCEDURE trgtest();
 \! pg_repack --dbname=contrib_regression --table=trg4
 
 --